Studies are being carried out to determine ventricular recovery properties in experimental animals during control conditions and in some disease states. The findings are being related to ECG waveform to improve understanding of the physiologic basis of the T wave and to develop methods of ECG analysis to improve the diagnostic and prognostic utility of the ECG. The effects of electrotonic interations during recovery in normal and disease states and the manifestation of these interactions on T waveform is being investigated. In addition, the ECG manifestations of inhomogeneity of recovery are being analyzed with new methods based on the ORST area in body surface potential maps as possible indices of vulnerability to arrhythmias.